Method And System For A Bi-Directional Multi-Wavelength Receiver For Standard Single-Mode Fiber Based On Grating Couplers

ABSTRACT

Methods and systems for a bi-directional receiver for standard single-mode fiber based on grating couplers may include, in an integrated circuit, a multi-wavelength grating coupler, and first and second optical sources coupled to the integrated circuit: coupling first and second source optical signals at first and second wavelengths into the photonically-enabled integrated circuit using the first and second optical sources, where the second wavelength is different from the first wavelength, receiving a first optical data signal at the first wavelength from an optical fiber coupled to the multi-wavelength grating coupler, and receiving a second optical data signal at the second wavelength from the optical fiber. Third and fourth optical data signals at the first and second wavelengths may be communicated out of the optoelectronic transceiver via the multi-wavelength grating coupler.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application is a continuation of U.S. application Ser. No.16/030,391 filed on Jul. 9, 2018, which is a continuation of U.S.application Ser. No. 15/676,197 filed on Aug. 14, 2017, now U.S. Pat.No. 10,020,884, which is a continuation of U.S. patent application Ser.No. 14/612,496 filed on Feb. 3, 2015, now U.S. Pat. No. 9,735,869, whichclaims priority to and the benefit of U.S. Provisional Application No.61/965,611 filed on Feb. 3, 2014, and U.S. Provisional Application No.62/122,718 filed on Oct. 28, 2014, each of which is hereby incorporatedherein by reference in its entirety.

FIELD

Certain embodiments of the disclosure relate to semiconductor photonics.More specifically, certain embodiments of the disclosure relate to amethod and system for a bi-directional multi-wavelength transceiver forstandard single-mode fiber based on grating couplers.

BACKGROUND

As data networks scale to meet ever-increasing bandwidth requirements,the shortcomings of copper data channels are becoming apparent. Signalattenuation and crosstalk due to radiated electromagnetic energy are themain impediments encountered by designers of such systems. They can bemitigated to some extent with equalization, coding, and shielding, butthese techniques require considerable power, complexity, and cable bulkpenalties while offering only modest improvements in reach and verylimited scalability. Free of such channel limitations, opticalcommunication has been recognized as the successor to copper links.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present disclosure as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY

A system and/or method for a bi-directional multi-wavelength transceiverfor standard single-mode fiber based on grating couplers, substantiallyas shown in and/or described in connection with at least one of thefigures, as set forth more completely in the claims.

Various advantages, aspects and novel features of the presentdisclosure, as well as details of an illustrated embodiment thereof,will be more fully understood from the following description anddrawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a block diagram of a photonically-enabled integrated circuitwith a bi-directional multi-wavelength transceiver, in accordance withan example embodiment of the disclosure.

FIG. 1B is a diagram illustrating an exemplary photonically-enabledintegrated circuit with bi-directional multi-wavelength gratingcouplers, in accordance with an exemplary embodiment of the disclosure.

FIG. 1C is a diagram illustrating a photonically-enabled integratedcircuit coupled to an optical fiber cable, in accordance with an exampleembodiment of the disclosure.

FIG. 2 illustrates a bi-directional multi-wavelength transceiver forstandard single-mode fiber, in accordance with an example embodiment ofthe disclosure.

FIG. 3 illustrates a triple grating coupler, in accordance with anexample embodiment of the disclosure.

FIG. 4 illustrates another example of a triple grating coupler, inaccordance with an example embodiment of the disclosure

DETAILED DESCRIPTION

Certain aspects of the disclosure may be found in a method and systemfor a bi-directional multi-wavelength transceiver for standardsingle-mode fiber based on grating couplers. Exemplary aspects of thedisclosure may comprise, a photonically-enabled integrated circuitcomprising an optoelectronic transceiver, and first and second gratingcouplers, where the photonically-enabled integrated circuit is operableto: communicate a first optical data signal from the optoelectronictransceiver into a first fiber coupled to the first grating coupler,receive a second optical data signal from the first optical fibercoupled to the first grating coupler, communicate a third optical datasignal from the optoelectronic transceiver into a second optical fibercoupled to the second grating coupler, and receive a fourth optical datasignal from the second optical fiber coupled to the second gratingcoupler. The first and third optical data signals may be at a firstwavelength, and the second and fourth optical data signals may be at asecond wavelength different from the first wavelength. Thephotonically-enabled integrated circuit may comprise a complementarymetal-oxide semiconductor (CMOS) chip. The first and second opticalfibers may comprise single mode fibers. The first optical data signalmay be generated utilizing a first optical source assembly coupled tothe photonically-enabled integrated circuit and the second optical datasignal may be generated utilizing a second optical source assemblycoupled to the photonically-enabled integrated circuit.

FIG. 1A is a block diagram of a photonically-enabled integrated circuitwith a bi-directional multi-wavelength transceiver, in accordance withan example embodiment of the disclosure. Referring to FIG. 1A, there isshown optoelectronic devices on a photonically-enabled integratedcircuit 130 comprising optical modulators 105A-105D, photodiodes111A-111D, monitor photodiodes 113A-113H, and optical devices comprisingcouplers 103A-103J, optical terminations 115A-115D, and grating couplers117A-117D. There are also shown electrical devices and circuitscomprising amplifiers 107A-107D, analog and digital control circuits109, and control sections 112A-112D. The amplifiers 107A-107D maycomprise transimpedance and limiting amplifiers (TIA/LAs), for example.In an example scenario, the photonically-enabled integrated circuit 130comprises a CMOS photonics die.

Optical signals are communicated between optical and optoelectronicdevices via optical waveguides 110 fabricated in thephotonically-enabled integrated circuit 130. Single-mode or multi-modewaveguides may be used in photonic integrated circuits. Single-modeoperation enables direct connection to optical signal processing andnetworking elements. The term “single-mode” may be used for waveguidesthat support a single mode for each of the two polarizations,transverse-electric (TE) and transverse-magnetic (TM), or for waveguidesthat are truly single mode and only support one mode whose polarizationis TE, which comprises an electric field parallel to the substratesupporting the waveguides. Two typical waveguide cross-sections that areutilized comprise strip waveguides and rib waveguides. Strip waveguidestypically comprise a rectangular cross-section, whereas rib waveguidescomprise a rib section on top of a waveguide slab.

The optical modulators 105A-105D comprise Mach-Zehnder or ringmodulators, for example, and enable the modulation of thecontinuous-wave (CW) laser input signal. The optical modulators105A-105D may comprise high-speed and low-speed phase modulationsections and are controlled by the control sections 112A-112D. Thehigh-speed phase modulation section of the optical modulators 105A-105Dmay modulate a CW light source signal with a data signal. The low-speedphase modulation section of the optical modulators 105A-105D maycompensate for slowly varying phase factors such as those induced bymismatch between the waveguides, waveguide temperature, or waveguidestress and is referred to as the passive phase, or the passive biasingof the MZI.

The outputs of the modulators 105A-105D may be optically coupled via thewaveguides 110 to the grating couplers 117A-117D. The couplers 103C-103Jmay comprise four-port optical couplers, for example, and may beutilized to sample or split the optical signals generated by the opticalmodulators 105A-105D, with the sampled signals being measured by themonitor photodiodes 113A-113H. The unused branches of the directionalcouplers 103C-103J may be terminated by optical terminations 115A-115Dto avoid back reflections of unwanted signals.

The grating couplers 117A-117H comprise optical gratings that enablecoupling of light into and out of the photonically-enabled integratedcircuit 130. The grating couplers 117A-117D may be utilized to couplelight received from optical fibers into and out of thephotonically-enabled integrated circuit 130. The grating couplers117A-117D may comprise single polarization grating couplers (SPGC),polarization splitting grating couplers (PSGC), demultiplexing gratingcouplers (DMGC), and/or bi-wavelength polarization-multiplexing gratingcouplers (PMGC). Example PSGC and PMGC structures are described inincorporated application Ser. No. 62/122,718 filed on Oct. 28, 2014. Ininstances where a PSGC or a PMGC is utilized, two input, or output,waveguides may be utilized. In instances where a DMGC is utilized, fourinput, or output, waveguides may be utilized.

The optical fibers may be epoxied, for example, to the CMOS chip, andmay be aligned at an angle from normal to the surface of thephotonically-enabled integrated circuit 130 to optimize couplingefficiency. In an example embodiment, the optical fibers may comprisesingle-mode fiber (SMF) and/or polarization-maintaining fiber (PMF).

In an example embodiment, optical signals may be generated by the CWlaser In 101A and 101B, which may comprise an assembly mounted to thephotonically-enabled integrated circuit 130, and may generate differentwavelengths for multi-wavelength operation of the photonically-enabledintegrated circuit 130. For example, 1310 nm and 1490 nm wavelengthoptical signals may be generated in the CW laser In 101A and 101B,respectively. Accordingly, the grating couplers 103A and 103B may beconfigured for a desired wavelength. In another example scenario, eachCW laser In 101A and 101B may comprise multiple wavelength outputs andthe grating couplers 103A and 103B may be configured to receive multiplewavelengths.

The photodiodes 111A-111D may convert optical signals received from thegrating couplers 117A-117D into electrical signals that are communicatedto the amplifiers 107A-107D for processing. In another embodiment of thedisclosure, the photodiodes 111A-111D may comprise high-speedheterojunction phototransistors, for example, and may comprise germanium(Ge) in the collector and base regions for absorption in the 1.3-1.6 μmoptical wavelength range, and may be integrated on a CMOSsilicon-on-insulator (SOI) wafer.

The analog and digital control circuits 109 may control gain levels orother parameters in the operation of the amplifiers 107A-107D, which maythen communicate electrical signals off the photonically-enabledintegrated circuit 130. The control sections 112A-112D compriseelectronic circuitry that enable modulation of the CW laser signalreceived from the splitters 103A and 103B. The optical modulators105A-105D may require high-speed electrical signals to modulate therefractive index in respective branches of a Mach-Zehnder interferometer(MZI), for example. In an example embodiment, the control sections112A-112D may include sink and/or source driver electronics that mayenable a bidirectional link utilizing a single laser.

In operation, the photonically-enabled integrated circuit 130 may beoperable to transmit and/or receive and process optical signals. Opticalsignals may be received from optical fibers by the grating couplers117A-117D and converted to electrical signals by the photodetectors111A-111D. The electrical signals may be amplified by transimpedanceamplifiers in the amplifiers 107A-107D, for example, and subsequentlycommunicated to other electronic circuitry (not shown) in thephotonically-enabled integrated circuit 130.

An integrated transceiver may comprise at least three opticalinterfaces, including two transmitter input ports to interface to the CWlight sources, labeled as CW Laser In 101A and 101B; and atransmitter/receiver input/output port to interface to the fibercarrying the optical signal, labeled Optical Signals In/Out.

Integrated photonics platforms allow the full functionality of anoptical transceiver to be integrated on a single chip. An opticaltransceiver chip contains optoelectronic circuits that create andprocess the optical/electrical signals on the transmitter (Tx) and thereceiver (Rx) sides, as well as optical interfaces that couple theoptical signals to and from a fiber. The signal processing functionalitymay include modulating the optical carrier, detecting the opticalsignal, splitting or combining data streams, and multiplexing ordemultiplexing data on carriers with different wavelengths.

In an example embodiment of the disclosure, external continuous-wave(CW) light sources are used. This architecture allows heat sinking andtemperature control of the source separately from thephotonically-enabled integrated circuit 130. External light sources mayalso be connected to the photonically-enabled integrated circuit 130 viaa fiber interface. The light source assemblies may be attached to thephotonically-enabled integrated circuit 130.

In an example scenario, a method is disclosed for a multi-wavelengthbi-directional transceiver. Grating couplers that receive and transmitmore than one wavelength may be utilized to launch a plurality ofwavelengths down a single fiber. Additionally, optical signals maytravel in either direction through grating couplers, i.e., the opticalsignals may be received from a fiber and communicated to waveguides onthe photonically-enabled integrated circuit 130 or optical signalsreceived from waveguides may be launched in the photonically-enabledintegrated circuit 130 and launched into an optical fiber.

FIG. 1B is a diagram illustrating an exemplary photonically-enabledintegrated circuit with bi-directional multi-wavelength gratingcouplers, in accordance with an exemplary embodiment of the disclosure.Referring to FIG. 1B, there is shown the photonically-enabled integratedcircuit 130 comprising electronic devices/circuits 131, optical andoptoelectronic devices 133, light source interfaces 135A and 135B, achip front surface 137, an optical fiber interface 139, and a CMOS guardring 141.

The light source interfaces 135A/135B and the optical fiber interface139 comprise grating couplers, for example, that enable coupling oflight signals via the CMOS chip surface 137, as opposed to the edges ofthe chip as with conventional edge-emitting/receiving devices. Couplinglight signals via the chip surface 137 enables the use of the CMOS guardring 141 which protects the chip mechanically and prevents the entry ofcontaminants via the chip edge.

The electronic devices/circuits 131 comprise circuitry such as theamplifiers 107A-107D and the analog and digital control circuits 109described with respect to FIG. 1A, for example. The optical andoptoelectronic devices 133 comprise devices such as the couplers103A-103K, optical terminations 115A-115D, grating couplers 117A-117H,optical modulators 105A-105D, high-speed heterojunction photodiodes111A-111D, and monitor photodiodes 113A-113I, described with respect toFIG. 1A, for example.

In an example scenario, the light source interfaces 135A/135B and theoptical fiber interface 139 may be bi-directional, so that opticalsignals may be communicated in either direction, i.e., received from asource external to the chip or communicated from the chip to an externaldevice. In addition, the light source interfaces 135A/135B and theoptical fiber interface 139 may comprise grating couplers that areconfigured for two or more wavelengths. In an example scenario, thegrating couplers may be operable to couple both 1310 nm and 1490 nmoptical signals.

FIG. 1C is a diagram illustrating a photonically-enabled integratedcircuit coupled to an optical fiber cable, in accordance with an exampleembodiment of the disclosure. Referring to FIG. 1C, there is shown thephotonically-enabled integrated circuit 130 comprising the chip surface137, and the CMOS guard ring 141. There is also shown a fiber-to-chipcoupler 145, an optical fiber cable 149, and an optical sourceassemblies 147A and 147B.

The photonically-enabled integrated circuit 130 comprising theelectronic devices/circuits 131, the optical and optoelectronic devices133, the light source interfaces 135A/B, the chip surface 137, and theCMOS guard ring 141 may be as described with respect to FIG. 1B.

In an example embodiment, the optical fiber cable may be affixed, viaepoxy for example, to the CMOS chip surface 137. The fiber chip coupler145 enables the physical coupling of the optical fiber cable 149 to thephotonically-enabled integrated circuit 130 and may be configured toplace the optical fibers in the optical fiber cable 149 at an angle fromnormal to the chip surface 137 for optimum coupling efficiency into thegrating coupler. The angle may be defined by the grating coupler designand wavelength of light to be coupled, for example.

In an example scenario, the optical source assemblies 147A and 147B maycommunicate optical signals at a plurality of wavelengths. In oneexample, each optical source assembly 147A and 147B generates adifferent wavelength, such as 1310 nm and 1490 nm, for example.

FIG. 2 illustrates a bi-directional multi-wavelength transceiver forstandard single-mode fiber, in accordance with an example embodiment ofthe disclosure. FIG. 2 may share any aspects of FIGS. 1A-1C. Referringto FIG. 2, there is shown bi-directional multi-wavelength transceiver200 that may be integrated on a chip, such as the photonically-enabledintegrated circuit 130. The bi-directional multi-wavelength transceiver200 may comprise an electronic interface 201, light source assemblies203A and 203B, a transmitter module 205, a receiver module 207, andgrating couplers 209A and 209B.

The electronic interface 201 may comprise suitable circuitry, logic,and/or code that is/are operable to receive and transmit electricalsignals from external devices and also to and from the transmittermodule 205 and receiver module 207. In an example scenario, theelectronic interface 201 may comprise the electronic interface for aquad small form-factor pluggable package (QSFP) using 4×26 GB/selectronics thereby generating 100 GB/sec signals but with 26 GB/selectronics.

The light source assemblies 203A and 203B may comprise one or morelasers in an assembly that may be bonded to the top surface of the chipcomprising the bi-directional multi-wavelength transceiver 200. Theassemblies may comprise lenses, rotators, reflectors, and polarizers,for example. Each of the light source assemblies 203A and 203B maycomprise a laser with a different wavelength, 1310 nm and 1490 nm, forexample. In this manner, two wavelengths may be processed by thebi-directional multi-wavelength transceiver 200, doubling the systemspeed without requiring double-speed electronics.

The Tx module 205 may comprise optical, optoelectronic, and/orelectronic devices for receiving electrical signals from the electronicinterface 201 an communicating modulated optical signals at wavelengthsλ1 and λ2 to the grating couplers 209A and 209B. Accordingly, the Txmodule 205 may comprise elements from FIG. 1A, such as the opticalmodulators 105A-105C, waveguides 110, control modules 112A-112D, andanalog and digital control circuits 109, for example.

Similarly, the Rx module 207 may comprise optical, optoelectronic,and/or electronic devices for receiving modulated optical signals atwavelengths λ₁ and λ₂ from the grating couplers 209A and 209B andcommunicating electrical signals to the electronic interface 201.Accordingly, the Rx module 207 may comprise elements from FIG. 1A, suchas the photodiodes 111A-111D, amplifiers 107A-107D, and analog anddigital control circuits 109.

Since the grating couplers 209A and 209B communicate optical signals ofdifferent wavelength into and out of the chip, the Tx module 205 and theRx module 207 therefore support duplex operation, making the transceiver200 a bi-directional multi-wavelength transceiver that can communicate100 GB/s over two single-mode fibers. With the multi-wavelengthbi-directional operation there is no need to split the optical signalfrom the laser and thus no speed degradation with only pulse amplitudemodulation (PAM) penalty and combiner loss. Similarly, there is no needto multiplex/demultiplex with tuning, relevant to power consumption andcontrol loops, for example.

While FIG. 2 shows each grating coupler 209A and 209B receiving onewavelength optical signal and communicating the other wavelength signalout of the bi-directional multi-wavelength transceiver 200, thedisclosure is not so limited. Each grating coupler may be operable tocommunicate optical signals in either direction at one or morewavelengths, as illustrated by the grating couplers in FIGS. 3 and 4,for example.

The diffractive grating used in grating couplers can also be used as ademultiplexer by taking advantage of the special property of the gratingthat different wavelengths can be directed into different scatteringorders, therefore spatially separated, by the grating. One example ofthis is a demultiplexing grating coupler. A 1D DMGC comprises aone-dimensionally periodic grating. If the fiber above the gratingcoupler is tilted by a small angle with respect to the normal, along thedirection of periodicity, two wavelengths from the fiber can be coupledinto the plane of the chip in opposite directions.

FIG. 3 illustrates a triple grating coupler, in accordance with anexample embodiment of the disclosure. Referring to FIG. 3, there isshown triple grating coupler 300 with a fiber 301 and waveguides303A-303C. FIG. 3 may share any aspects of FIGS. 1A-2. The fiber 301 maycomprise a single mode fiber, for example, that may be operable tocommunicate signals into, and receive signals from, the triple gratingcoupler 300. The angle at which the fiber 301 shown in FIG. 3 is forillustrative purposes only, as the fiber 301 may be closer toperpendicular to the surface, or at a larger angle, depending on thedesign on the triple grating coupler 300.

Similarly, the waveguides 303A-303C may be operable to communicateoptical signals into the triple grating coupler 300 from the chip 130and/or may receive optical signals from the triple grating coupler 300via the fiber 301 to communicate to other components in the transceiver.The grates in the regions of the triple grating coupler 300 closest toeach of the waveguides 303A-303C may configure the wavelength of theoptical signal that is received from the fiber in that waveguide. In anexample scenario, the grates may comprise curved waveguide sections,each configured for a desired wavelength. The focusing gratings in eachsection may be designed appropriately by taking into account the phasematching condition between the fiber mode and the grating mode in eachdirection. After the proper phase matching is computed, the orientationof the lines making up the 1D grating components is altered. Forinstance, the grating becomes slightly tilted from the horizontaldirection to cause the mode incoming from the vertical direction to bescattered into the fiber. Other relative orientations between the fiberand the two waveguides are also conceivable.

In addition, the waveguides 303A-303C may communicate optical signals atan appropriate wavelength to the corresponding arm of the triple gratingcoupler 300, determined by which laser source generates the signal.

FIG. 4 illustrates another example of a triple grating coupler, inaccordance with an example embodiment of the disclosure. FIG. 4 mayshare any aspects of FIGS. 1A-3. Referring to FIG. 4, there is showntriple grating coupler 400, a fiber 401, and waveguides 403A-403C. Thetriple grating coupler 400 may comprise a 2D array of scatteringelements. One typical 2D grating structure is based on a combination oftwo one-dimensionally periodic gratings. The two gratings direct lightarriving at it from approximately perpendicular directions, andtherefore the 2D grating is topologically similar to a square lattice,where the scatterers are placed at the intersections of the two 1Dgratings. A 2D grating with a triangular/hexagonal symmetry, one exampleof which is shown in FIG. 4, allows the multiplexing of more than twowavelengths. It is based on a combination of three one-dimensionallyperiodic gratings.

In an example scenario, the three input waveguides 403A-403C are atapproximately 120° angle with each other. The scatterers may be placedat the vertices of the lattice. The periodicity of the grating in thethree different directions corresponds to the three wavelengths λ₁, λ₂,and λ₃, of the light being coupled to the fiber, according to the phasematching conditions at each wavelength. As in previous figures, theangle at which the fiber 401 is placed with respect to the plane of thetriple grating coupler 400 is merely an example for clarity of thefigure, and may be configured at a desired angle based on the design ofthe grates in the triple grating coupler 400.

In operation, the triple grating coupler 400 may receive optical signalsat three wavelengths, λ₁, λ₂, and λ₃, via the optical fiber 401 andcommunicate each wavelength to a separate waveguide 403A-403C. Inaddition, optical signals of any of the three wavelengths may becommunicated from the waveguides 403A-403C to the triple grating coupler400 and into the optical fiber 401, thereby supporting full duplexoperation in a single fiber at multiple wavelengths.

In an example embodiment, a method and system are disclosed for abi-directional multi-wavelength transceiver for standard single-modefiber based on grating couplers. In this regard, aspects of thedisclosure may comprise, in a photonically-enabled integrated circuitcomprising an optoelectronic transceiver, a multi-wavelength gratingcoupler, and first and second optical source assemblies coupled to thephotonically-enabled integrated circuit: coupling a first source opticalsignal at a first wavelength into the photonically-enabled integratedcircuit using the first optical source assembly, coupling a secondsource optical signal at a second wavelength different from the firstwavelength into the photonically-enabled integrated circuit using thesecond optical source assembly, receiving a first optical data signal atthe first wavelength from an optical fiber coupled to themulti-wavelength grating coupler, and receiving a second optical datasignal at the second wavelength from the optical fiber.

A third optical data signal at the first wavelength may be communicatedout of the optoelectronic transceiver via the multi-wavelength gratingcoupler. A fourth optical data signal at the second wavelength may becommunicated out of the optoelectronic transceiver via themulti-wavelength grating coupler. The photonically-enabled integratedcircuit may comprise a complementary metal-oxide semiconductor (CMOS)chip. The optical fiber may comprise a single mode fiber. Themulti-wavelength grating coupler may comprise sections of curvedwaveguides, a first section configured for the first wavelength and asecond section configured for the second wavelength. Themulti-wavelength grating coupler may comprise a two-dimensional array ofscattering elements located at intersections of three one-dimensionallyperiodic gratings.

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As usedherein, for example, a particular processor and memory may comprise afirst “circuit” when executing a first one or more lines of code and maycomprise a second “circuit” when executing a second one or more lines ofcode. As utilized herein, “and/or” means any one or more of the items inthe list joined by “and/or”. As an example, “x and/or y” means anyelement of the three-element set {(x), (y), (x, y)}. In other words, “xand/or y” means “one or both of x and y”. As another example, “x, y,and/or z” means any element of the seven-element set {(x), (y), (z), (x,y), (x, z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means“one or more of x, y and z”. As utilized herein, the term “exemplary”means serving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “e.g.,” and “for example” set off lists ofone or more non-limiting examples, instances, or illustrations. Asutilized herein, circuitry is “operable” to perform a function wheneverthe circuitry comprises the necessary hardware and code (if any isnecessary) to perform the function, regardless of whether performance ofthe function is disabled or not enabled (e.g., by a user-configurablesetting, factory trim, etc.).

While the disclosure has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present disclosure. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present disclosure without departing from itsscope. Therefore, it is intended that the present disclosure not belimited to the particular embodiments disclosed, but that the presentdisclosure will include all embodiments falling within the scope of theappended claims.

1. (canceled)
 2. A method for communication, the method comprising: inan integrated circuit comprising a multi-wavelength grating coupler andone or more optical sources coupled to the integrated circuit: couplingone or more source optical signals into the integrated circuit using oneor more optical sources; receiving a first optical data signal at afirst wavelength from an optical fiber coupled to the multi-wavelengthgrating coupler; and receiving a second optical data signal at a secondwavelength from the optical fiber coupled to the multi-wavelengthgrating coupler.
 3. The method according to claim 2, comprisingcommunicating a third optical data signal at the first wavelength out ofthe integrated circuit via the multi-wavelength grating coupler.
 4. Themethod according to claim 3, comprising communicating a fourth opticaldata signal at the second wavelength out of the integrated circuit viathe multi-wavelength grating coupler.
 5. The method according to claim2, wherein the integrated circuit comprises a complementary metal-oxidesemiconductor (CMOS) chip.
 6. The method according to claim 2, whereinthe optical fiber comprises a single mode fiber.
 7. The method accordingto claim 2, wherein the multi-wavelength grating coupler comprisessections of curved waveguides, a first section configured for the firstwavelength and a second section configured for the second wavelength. 8.The method according to claim 2, wherein the multi-wavelength gratingcoupler comprises a two-dimensional array of scattering elements locatedat intersections of two one-dimensionally periodic gratings.
 9. A systemfor communication, the system comprising: an integrated circuitcomprising a multi-wavelength grating coupler and one or more opticalsources coupled to the integrated circuit, said integrated circuit beingoperable to: couple one or more source optical signals into theintegrated circuit using the one or more optical sources; receive afirst optical data signal at a first wavelength from an optical fibercoupled to the multi-wavelength grating coupler; and receive a secondoptical data signal at a second wavelength from the optical fibercoupled to the multi-wavelength grating coupler.
 10. The systemaccording to claim 9, wherein the integrated circuit is operable tocommunicate a third optical data signal at the first wavelength out ofthe integrated circuit via the multi-wavelength grating coupler.
 11. Thesystem according to claim 9, wherein the integrated circuit is operableto communicate a fourth optical data signal at the second wavelength outof the integrated circuit via the multi-wavelength grating coupler. 12.The system according to claim 9, wherein the integrated circuitcomprises a complementary metal-oxide semiconductor (CMOS) chip.
 13. Thesystem according to claim 9, wherein the optical fiber comprises asingle mode fiber.
 14. The system according to claim 9, wherein themulti-wavelength grating coupler comprises sections of curvedwaveguides, a first section configured for the first wavelength and asecond section configured for the second wavelength.
 15. The systemaccording to claim 9, wherein the multi-wavelength grating couplercomprises a two-dimensional array of scattering elements located atintersections of two one-dimensionally periodic gratings.
 16. A systemfor communication, the system comprising: an integrated circuitcomprising a grating coupler, said integrated circuit being operable to:communicate a first optical data signal from the integrated circuit intoa fiber coupled to the grating coupler; receive a second optical datasignal from the optical fiber coupled to the grating coupler;communicate a third optical data signal from the integrated circuit intothe optical fiber coupled to the grating coupler; and receive a fourthoptical data signal from the optical fiber coupled to the gratingcoupler.
 17. The system according to claim 16, wherein the first andthird optical data signals are at a first wavelength.
 18. The systemaccording to claim 17, wherein the second and fourth optical datasignals are at a second wavelength different from the first wavelength.19. The system according to claim 16, wherein the integrated circuitcomprises a complementary metal-oxide semiconductor (CMOS) chip.
 20. Thesystem according to claim 16, wherein the optical fiber comprises asingle mode fiber.
 21. The system according to claim 16, comprisinggenerating the first optical data signal utilizing one or more opticalsources coupled to the integrated circuit.